Production of complex sounds



April 6, 1937.

M. DAVIS PRODUCTION OF COMPLEX SOUNDS Filed Jan 26, 19:53 12 Sheets-Sheet 1 INVENTOR ATTORNEY April 6, 1937. M. DAVIS PRODUCTION OF COMPLEX SOUNDS F'iled Jan. 26, 1933 l2 Sheets-Sheet 2 INVENTOR m AQW..

ATTORNEY .April 6, 1937.. M. DAVIS PRODU-QTION OF COMPLEX sofimzs Filed Jan. 26, 1933 I 12 Sheets-Sheet 3 INVENTOR ATTORNEY April 6, 1937. M. DAVIS- PRODUCTION OF COMPLEX SOUNDS Filed Jan. 26; 1933 12 Sheets-Shget 4 M Jab-d April 6, 1937. M. DAVIS- PRODUCTION OF COMPLEX ISOXYJNDS 12 Sheets-Sheet 5 Filed Jan. 26, 1933 uulan'a'no April 6, 1937. M. DAVIS PRODUCTION OF COMPLEX SOUNDS Filed Jan. 26, 1933 12 Sheets-Sheet 6 gm' ntoc IHIM S mm $77.99 70/058 ai /i0 All SZZNFW97] QL Ap 6, 1937. M. DAVIS PRODUCTION OF COMPLEX SOUNDS Filed Jan. 26, 195s '12 Sheets-Sheet a i l w k m R1 RT wk 9: T

April 6, 1937; M. DAVIS V FRODUCTION OF CCMPLEX souuns 12 Sheets-Sheet 9 Filed Jan. 26, 1933 INVENTOR ATTORNEY M. DAVIS 2,075,802 PRODUCTION O COMPLEX SOUNDS Filed Jan. 2a, 1933 12 Sheets-Sheet 1o m vww kw hmfiv v 3% MNN NNN/ April 6, 1937.

' April 6, 1937. M. DAVIS PRODUCTION OF COMPLEX SOUNDS l2 Sheets-Sheet 11 -1=.' iied Jan. 26, 1933 QvN M. DAVIS PRODUCTION OF COMPLEX SOUNDS April 6, 1937,

12' Sheets-Sheet 12 Filed Jan. 26, 1933 Patented Apr. 6, 1937 r 2,075,802 rnonUc'rroN or COMPLEX SOUNDS Merlin Davis, Milton, Pa.

Application January 26, 1933, Serial a... 653,684 as Claims. (01. 84-1) (Granted under the act of March 3, 1883, as mended April 30, 1928; 370 0. G. 757) The invention described herein may be manuiactured and used by or for the- Government of the United States for governmental purposes only without the payment of any royalty thereon.

My invention relates to an instrument of underlying electrical principles for the production of complex sounds. As a musical instrument it offers complete control 'of quality or timbre during the rendition of a musical composition with limitless tonal variations at the immediate will of the operator. The scale in just temperament may be playedin the various keys of the major and minor modes upon a standard piano keyboard. It may be adapted for new scale formations.

Whenever any 'key of the keyboard of my instrument is struck, there is sounded along with the pitch or frequency which is apparent, or fundamental, a number of other musical sounds whose frequencies ofvibration are 1, 2, 3, 4, 5, 6, 7 etc. times the fundamental frequency, respectively. The volume or loudness of these harmonies, so called, is made such that each may be independently controlled or in such a manner that they bear certain governable relations to each other. By regulating the intensity of these harmonic tones which accompany the fundamental the quality or timbre of the combined tone is varied such thatexisting instruments may be simulated or. new tones originated which it may be impossible to produce by means of prior musical instruments. As a further means of changing the quality it is arranged that after a note is struck some of its harmonics, as desired, may be made to swell in to volume before others. The degree of the time lag in the reis at'the control of the optarded harmonicserator. v I By means of my invention tremolo eflects are made possible. ..'in intensity control scaleof cution is improved by means for automatically maintaining a constant volume of sound as the number of ,notes to a chord is increased.

An instrument with a fixed keyboard such as ease of operation.

in the accompanying drawings in which: sensibly equal gradatlonsis a feature; while exe- V PATENT OFFICE serving the true pitch scale relations by means for shifting, in eflect, this keyboard to the others just mentioned by the use of key signature stops. If a piano werebuilt using the just tempered scale with the seven keyboards, as outlined, each 5 of these would be divided into groups of seven keys or octaves whose'notes would be double the frequency of their corresponding predecessor. The vibration frequency of the seven keys of each such octave group, comprising the scale, 10 would each have a frequency which would be a definite multiple of the lowest note of the group, called the key note. These same definite multiples of a key note would apply in each group for all the'keyboards; The vibration ire-'15 quency of the notes in the various keyboards would differ. The first would start in the bass with an established standard pitch while the ,others would each successively have its lowest note of a group one degree higher in' the scale. 20 The pitches on the seven manuals would corre-v spond to those of the major key signatures. Such a plural keyboard instrument would naturally be too cumbersome. These manuals are condensed into one on the practical piano thereby deviating somewhat from the pitch relation required for true harmony Such a compromise keyboard necessitates the introduction of the musicalnotation of key signature to facilitate execution. The use of the key signature stops in "my, electricalinstnnnent eliminates the need for keeping a signature in mind. This electrical instrument is not limited to the use 0 the intervals to which we are accustomed in e equal or just tempered scales but would allow other 35 scale formations to be employed with the same For the purpose of illustration a plurality of forms of my device are diagrammatically shown 40 Figurev 1 is'a side view showing the general arrangement of one form.

Figure 2 diagrammatically .shows a portion of one form of record which I may use.

Figure 3' shows a portion of an opaque disk. provided with a plurality of narrow transparent radial light openings.

Figure 4 is a side view, partly in section illustrating one form of shutter operating mecha nism.

Figure 4a is a plan view of part of the mechanism shown in Figure 4 and comprising elements 4| to 60 inclusive.

Figure 5 is a detail of a foot pedal and linkage 5 shown in Fig. 4.

Figure 6 is a side view of a stop deviceshown in Fig. 4.

Figure? is a fragmentary side view of two of the shutters and some of their accompanying. l0 mechanism which appear in front view in Fig. 4.

Figure 8 shows an intensity control circuit.

Figure 9 is a view of a mechanism for producing tremulous effects.

Figure 10 shows a portion of a record which may be used with other modifications of my invention.

Figure 11 is a diagram showing another form of my invention in which a special form of radiant energy emitter is used.

Figure 12 illustrates a modification provided with means for varying the current passing.

through multiple photoelectric "elements.

Figure 12a shows a top view of the photo-cell 8| illustrated in Figure 12.

Figure'13 is a diagrammatic view of an apparatus for making my shaded records by varying the exposure of a line of light on a revoluble photographic plate.

Figure 14 is a diagrammatic detail view ofmy apparatus for driving the record used in Figure 13.

In Figures 15 and 16 another modification of my invention having no rotating disks is shown.

Figure 17 illustrates one form of records which which may be produced by the circuit shown in Fig. 18. Figure 22 is a side view fication in which the revoluble slotted disk shown in Fig. 1 is replaced by a slotted endless belt or equivalent.

Figure 23 is a plan view of a portion of this modification.

Figure 24 is a view of another modification in which a slotted revoluble cylinder, or equivalent, i' eiplafes my slotted disks I and 1' shown in Figure 25 is an end view of Figure 24.

Figure 26 is a side view of a portion of a further modification, partly in section, of the form shown in'Figure 24 but differing in structure by the utilization of two sets of shutters for pitch and tone quality control in place of one set of shutters and a series of light sensitive cells. Figure 26a is a side view of a modification,

: partly in section, of the form shown in Figure 26 but difiering in structure by the fact that the elongated axially placed light sensitive cell is replaced by a light source.

Figure 27 is an end view of a portion of .the modification shown in Figure 26.

Figure 28. is a perspective view of a further modification in which my revoluble slotted disks 1 and I are replaced by stationary slotted plates and co-operating reciprocable plates having light transmitting openings.

Figure 28a is an enlarged view of record pattern F shown diagrammatically in Figure 28.

of a further modi- One form of my invention is illustratedin Figures 1 to 9, inclusive, the general assembly being diagrammatically shown in Figure 1..

In this-form audible sounds are emitted by a loudspeaker I, in the output of 'a circuit such as a capacitance resistance amplifier 3. The lnput of the amplifier is provided with parallel connected light sensitive elements, shown, as light sensitive cells2 and 2'.

Light supplied by incandescent lampsl and 4 is thrown upon controlling shutter means 5 and 5', shownindetail inFigures 4 and 7. My stationaryrecords 6 and 6' are provided with transparent openings of sine wave proportions or are provided with other means for varying the intensityot-light permitted to pass therethrough as by varying the translueency of my record in sine wave proportions as detailed in Fig. 2. Adjacent to myrecords 6 and 6' and between said records and the cells 2 and 2' I mount revoluble disks I and "I' each ofwhich is provided with a plurality of radial slots shown in detail in Fig.- 3.. My records and slotted disks serve as a means for producing a desired. pitch of sound emitted from the loud speaker I. 'I'L'I'he proper illumination ofthe shutters 5 and 5 may be supplied with the aid of parabolic reflectors 8 and 8' and spherical mirrors 9 and 9' placed on opposite sides of the lamps 4 and '4'.

The parallel rays of light which rnay be allowed to pass through the shutter means 5 and 5', my-records 6 and B and my revoluble disks 1 and-J. are concentrated upon the light sensitive cells 2 and 2 by means of a second-set of .parabolic reflectors l0 and Hi.

The pitch of the sounds produced by my -apparatus may alsobe. governed by varying the spied of rotation'of my disks 1" and I the mer being driven through a train of gearing H and the latter being driven at a different speed through a similar train of gearing H, from a shaft lit a speed change mechanism, shown as a. stepped pulley M with friction driven pulleys, l5, mounted on a shaft which is driven by a constant speed motor 16 through suitablespeed reducing means such as a belt drive, while means lea may be provided for'varying the.

speed of this motor l6.

The revoluble disks 1 and 'I' diner in their.

number [of slots and are operated at different speeds corresponding to the speed ratios 1 trains of gearing II or l2 respectively. The purpose of providing this dual form of mechanism is to provide pitches other than those present in the major mode. Each concentric. series of groups on either record comprises a fundamental pitch (group with single wave), with its octaves and harmonics, respectively. .Now the width of any one of these groups in one said concentric series is equal to the equal spacings between slots in that portion of the revoluble" slotted disk which crosses it and this distance in turn is determined for a required pitch of the fundamental of the series by dividing the annular concentric ring into a number of equal parts found by dividing a selected frequency in vibrations per second by the selected speed in revolutions per second. For

the

' 50 the notes of the C, D, E, and F, these in the just tempered scale have fractional relations of 4 nt of Eb 15 etc. These cannot be placed upon the same disk where 24 is used as a basic division for 25 and will not divide evenly into 24 and it would be necessary to have a fractionalpart of a wave on the record which would make it inoperative. A second disk is therefore provided to operate at a speed in connection with a new basic'number. for example 25, with which the notes outside of the major mode may be executed. It is to be understood that the second disk and light openings are only used for incidentals outside the major mode and not for semitones within the major scale in- -dicated in ordinary musical compositions by the flats and sharps in the key signature. The latter are provided by the first disk and light openings.

The shutter means 5 and 5', Figs. 4 and 7, are controlled by a series of keys I1 and I2; Fig. 1, each of which may be of the form of a piano keyboard of the usual form having white keys I! 35 and 20 and black keys I! and 20'. The white keys operate the shutter means 5 and the black keys operate the shutter means 5', as indicated diagrammatically by arrowed lines in Fig. 1. Said keys also operate electric switches in the 40 circuits to my series resistance inmy chord intensity controls (Flg. 8). The keys l5; I9, 20 and 22 may each have means to retiu'n it from its depressed position such as a spring 19a as shown inFig. 8.

In Figure 2 I have shown a portion of one of my records 6 in which my light transmitting openings 22, 22 are arranged in concentric rings as well-as in radial lines. I have arranged each radial line of openings in my records to cover scale of two octaves to enable the playing of chords within this range.

Successive radial lines. of openings inmy record in either the inner or outer series corresponds to a pitch which diilers from that of the first line 55 by being in progressive harmonic multiples of the first.

Thus my concentric series of records are so grouped that they include in addition to the initial fundamental note and the harmonics of this 60 note the higher octaves of the initial fundamental and their respective harmonics as well. My arrangement produces a relatively compact record thus avoiding records of excessive size, seeondly it utilizes the octaves existing within the 65 harmonic series to prevent duplication and thirdly, it provides for variation in quality by the choice and intensity of harmonics accompanying a fundamental or chord of fundamentals by varying the opening of the shutter means 5 and 5' 70 opposite the selected harmonics. e

' The pitches of the notes within the major scale fare related by simple ratios. To maintain these ratios which are those on my record, and at the same time start at higher or lower registers, that 75 is to say to play in Just temperament Iuse a friction speed change such as is shown in Figure 1. -The successive steps on the driving member are designed for speeds which will produce the proper pitches of the scale.

Only one of my signature stops 2| (Fig. 1) is used at a time, the remaining stops 2| being retained in normally inoperative position by any suitable means. such as a resilient catch, not

shown. -If my signature stops 2| (Figure l) are placed in the position of the key signatures of a given composition, the levers I! or 25 when depressed will vary the pitch throughout the major scale starting with a pitch or the key-note dependent upon the signature key depressed. Incidental notes are played on my black keys ll or 20. Due to the odd ratios of the latter, it is necessary to operate my disk i at a. diflerent speed from that of my disk 1' and on this account I have provided duplicate beam systems (Fig. l). The required speed differences are obtained by selecting bevel gears of the proper proportions for the gear trains II and 12.

My duplicate keyboards I1 and II are provided for the purpose of playing chords having notes within a range of two octaves. The white keys of one keyboard operate shutters cooperating with the black keys of the two keyboards cooperate with two similar sets of patterns, an octave apart,

on the record 6'.

Chord volume control is provided for through 24a in a magnetic field produced by the field pieces 24b. The armature is of such character common in the art (such as found in amperemeters and galvanorneters) where its movement about its axis is restrained by a tension means 240 such as a spring or the like. By this means the chord intensity of sound may be equalized while playing chords having a different number of notes contained therein. In this form course filament lamps l and 4' may be used with alternating current.

-A means for varying the lamp intensity for increasing or diminishing the volume of'sound may be provided by two three-element vapor tilled tubes 21 and circuit arrangement as shown in Fig. 8, which in conjunction with the filter circuit 21a simultaneously will supply filtered unidirectional current from an alternating current supply 21b.

For gradual diminution I provide a grid bias inductance coil 28 having a sliding contact 284 which may be operated by means of a foot pedal 28b, Fig. 1 through any suitable operative connection. This system minimizeslag which may be further eliminated if the-lamps 4 and 4' are 01' the gas-filled type and have fine ribbon filaments.

A second inductance 29 paralleling inductance 28 is provided with a plurality of taps 22 which divide this inductance into portions which give equal auditory volume gradations.

- 1o switches closes a low resistance shunt, and whenever a keyboard key is depressed it operates a switch 32 to first break one shunt, then as depressed further, closes a circuit through one of my series resistances 3| and simultaneously closes one of a plurality of single throw switches 32-A I in one of a plurality of normally open circuits to both lamps 4 and 4'. These controls may also serve to equalize the intensity of sound at the different pitches in the musical range. There are I as many switches 32 and 32a as there are keys i3 and I3, 20 and 20. While in Fig. 8 only one key i3 is shown,it is understood that the switches 32 and 32a shown as not associated with a key is 'merely a diagrammatic showing and are to be associated with such keys. Furthermore a circult is shown representing only two sets of switches whereas in a complete instrument the circiut as shown is extended to include all keys of the keyboard.

The form shown in Figs. 1 to 7 utilizes record patterns 22, 22a, 23, 23a, which may consist of openings representative of the pitches in the scale of one octave and their harmonics, respectively, but which is'extended to include a second octave and companion harmonics because of a limita tion of the mechanism to execute chords within more than the number of octaves present on a radial set of patterns of the records. In this form utilization is made of the fundamental and their 4 harmonics of higher octaves which are already present in the frequencies of the initial octave and its attendant harmonic frequencies as opposed to forms which shall be described later in which all the pitches on the keyboard in several octaves are 4 represented as separate elements on the record as well as their respective harmonic frequencies which results in duplication of record elements, representative of the same vibration frequency.

The mechanism shown by Fig. 4 of the general form illustra d in Fig. 1 consists of a series of lndependen y operated shutters 33 one for each of. the record elements representative of the frequencies of the'fundamentals .of one octave and their harmonics, respectively, as before mentioned '5 associated with one keyboard I! and a second octave with its harmonics associated with the second'keyboard l3 shown in Fig. -l. These shutters are selectively. opened by magnetically controlled I mechanisms manually set in operation by the keys of the keyboard such that pattern elements are uncovered representative of the fundamental and companion harmonic frequencies of any particular key of the keyboard which is depressed. The

relative degree of opening of these shutters, which in turn determines the relative intensity or.vol-' ume ofa fundamental and its harmonics which may be selected assigns the quality or tone color to the notes sounded. Manually operated control devices such as its foot pedals 54, push-pull handies 36 or revolvable knobs 41a (see Figs. 1 and 2) which in pipe organ terminology may be collectiveiy spoken of as stops serve this latter purpose. They control the intensity of selected fundamentals and harmonics either individually or collectively in varying amounts through attendant mechanism 46 to 63, working in conjunction with a magnetic and mechanical system which is coupled and has'parts in common with the aforesaid magnetically controlled mechanism associated with the keys of the keyboard and the shutters. If the same shutter is to serve as one of the fundamental notes or as the harmonics of 1 lower octave notes some automatic control device must be provided for selecting the degreeof opening of the various shutters representing the fundamental or harmonics of any key of the keyboard as it is depressed. The solenoids 45 are the aforesaid actuating means for automatic control of the degree of opening. The steps and their attendant mechanics provide the means for selection. The double action solenoids 36 are'the activating means for controlling which shutters are to be opened when the fundamental pitch desired is selected from the keys of the keyboard. Parts shown and identified in Fig. 4 as 24 and 25, 26a, do not enter into the above described phase of the operation and its function has been previously described. 7

There are as many double action solenoids 36 as there are hinged shuttenmembers 33. It has already been stated that the shutter members 33 control an individual record pattern and that the record 6 contains patterns of the fundamentals of an octave and the harmonics of each funda mental for each of the two keyboards. As previously stated, one keyboard starts an octave higher thanthe other. Therefore, each solenoid is connected by circuits containing selective switches 6| associated with each key of a key board corresponding with the fundamental and harmonic frequencies respectively which that key of the keyboard represents. However, for purposes of convenient illustration, the solenoids in Fig. 4 are shown as connected to the selective" switches 6| of only one key.

. The shutter means 5 and-5' shown particularly in Figs. 1, 4, and 7 comprising an opaque support So have a plurality of openings 51; each controlled by a hinged shutter member 33 (Figs. 4

and 7) there being only two shutters shown for convenience, the lower of which is shown partly opened and the upper closed. The openings to are arranged in radial lines corresponding to those of my lines of light transmitting openings 22 and23 of my records 6, each member 33 being operated by a wire 34 and by a spring 35, the latter tending "to return said members to open posi-.

tion when released by their wires34. Each of the wires 34 is connected to a plunger 36 of a twin coil solenoid having oppositely operating coils 31 and 33. Each solenoid plunger 36 is provided with an extension 33 terminating in a cushioned head 40. Thesolenoids connected with each radial line of shutter members are grouped so that the extensions 39 will pass through openings in one of aplurality of frames 4i having parallel sides and mountedforlimited reciprocating motion (Figs-4, 4a, and 6), the cushioned heads 43 being placed on the inside of said frames. Said frames 4| are also provided with a plurality of holes on the side opposite to said solenoid plungers, for receiving a plurality of rods 42 each provided with an inner cushioned head 43.

' Each rod 42 is pivotally attached to one of a plurality of pivoted levers 43a on the oppcsite-end, to each of which is pivotally attached a plunger extension 44 of a second solenoid 45. 'The up-, ward movements of each of said extensions 44 is selectively limited by one of a plurality of transby one 01 a plurality of manually revoluble cams 41, or by means of one or more of a plurality of flexible rods 48 which are rigidly mounted at one end, like a beam supported at one end, each rod being so proportioned as to give a diilerent curvature of flexure from those adjacent to it. Each of these flexible rods 48 is connected to one of a plurality of foot operated treadles 43, one 0! which is shown in side view in Figure. 4 in which the rod 48 is pivotally connected by a link 58, to a lever 5| provided with a manually adjustable pivot 52 and .a coupling link 53 to one of said treadles 49. which is yieldingly pressed by a restoring spring 54. Each pivot 52 is mounted in;

one end and adapted to serve as a stop for one or the floating bars 48 and connected between its ends by a link 58 to a lever 59 (Figs. 4 and 5) also coupled to the foot treadle 48 through a common shaft 80.

For the purpose of controlling the current to the solenoids 31 and 38 I provide a multiple contact switch 6| by means or which pressure on one of my keys (such as l9) first opens its contacts 38a of a circuit 38b through solenoid 38 and immediately closes the contact 31a of circuit 31b through the solenoid 31, furtherpressure operates solenoids ln other series in a similar manner, thus bringing in the harmonics of the fundamental sound. I

I introduce a variable inductance 62 in the circuit to the solenoid 31 for the purpose of retarding its action and also introduce a similar variable inductance 83 in the circuit to the-solenoid 38 for retarding the closing of the shutter elements 33. Several other ways of retarding the action of these solenoids may be used, such as of the form shown in Figure 1.

by means of separate short circuit windings. A switch 84 is provided in the circuit of the solenoid 31 for selectively cutting out any harmonic not desired.

In each of the independent circuits to my solenoids' 45 I place a switch 65 which is also closed by pressure on a corresponding key, such as I9.

In Figure 9 -I have shown a means for at will introducing light fluctuations for .producing a tremolo sound eifect. It consists of a revoluble translucent disk 86 having one portion 61 relatively transparent and another portion 88 relatively opaque with portions shading gradually from one into the other. This disk may be manually moved laterally in or out of the path of light rays by any suitable means, as by handle 58a.

A special form. of radiant energy emitter is shown in Figure 11 which may be used to replace lamps 4 and 4" and reflectors 8, 8', '9 and 9' A plurality of such radiant emitters 69 are arranged in radial lines to throw light through aligned light transmitting openings of the records 6. The emitters may have filaments 18 of identical construction. However, only one emitter 89 is shown in Fig. 11, but a plurality of such emitters are arranged in radial lines with respect to the axis of disc 1.

, Radiations from these emitters first pass through shield 1|, having openings 12, in alignment with corresponding light transmitting openings of the record 8. Light passing through the openings of the shield 12 is directed in parallel rays by means of a plurality oi radially arranged cylindrical lenses 13, upon my record 6 and disk 1.

Each emitter 89 is connected through a multiple contact switch 14 having flexiblemembers 14a enabling the closing of one or more circuits before the remaining circuits are closed, a plurality-of variable resistances 15, a second set of variable resistances 16, arranged inparallel, which are controlled by a flexible beam 11 or other equivalent, such as a multiple rotating arm resistor with varying widths, the circuit of each resistance 18 being controlled by one of a plurality of switches 18 to eliminate at will any harmonics not desired. Another variable resistance 19 is placed in one of two circuits arranged in parallel, in the other of which are place a plurality of switch controlled resistances 80 connected in parallel, both being connected with a common return lead to the lamp filaments. This electrical filament control identified by to 19 serves to accomplish what may be performed by the cam and flexible rod and pedal arrange- .ment of the form shown in Figure 4.

For obtaining equal chord intensity the switch and resistance circuits 3|; 32 and 32-A (Figure 8), may be connected in series in the circuit shown in Figure 11 between my battery and my variable resistance 1-3.

In a modification shown in Figure 12 I use a special form of photo-electric cell 8| which may be used to replace the photo cells 2--2' and reflectors l8 -l8' of the form shown in Figure 1 and which is provided with a plurality of concave cylindrical cathodes 82 provided with a light formed of a rod or wire placed at the axis of its companion cathode; The cathodes 82 are connected in parallel by a common lead 84 from a, battery 85, while each anode 83 is connected to one of a'plurality of terminals 86 of one of a plurality of multiple contact switches 81, having a plurality of electrically insulated conducting tongues 88. One of the photo-electric cells 8| is mounted opposite each line of radial openings in the record 6 with its axis substantially parallel with said radial openings. One of the revoluble disks 1 is placed between the record 8 and the light source and provides a means for sweeping each of the record openings with a radially moving beam of light. The rays which pass through the disk and record fall upon the concave surfaces of the'cathodes 82 which emit electrons that are drawn to their companion anodes 83 and thus complete the electric circuit which is substantially normally open when no light isfalling on the cathode.

For the purpose of carrying away the complative charge on the anodes 83, each is normally grounded through aplurality of switch contacts 89- to a common ground 98 for the purpose or sensitive coating on their concave faces each having a companion anode 83 which may be carrying away any small charges which may acfrom the record patterns comprising the fundamental and harmonic frequencies sounded by that key, which are included in patterns comprisin the fundamentals of'the lowest octave on the keyboard and their respective harmonics,

as shall be described in detail later, such that one cell element may serve One of the last mentioned circuits, associated" with each keyboard key, includes a variable resistance. 92a by means of which it may be .controlled and even opened, if. desired for fundamental intensity control. Each of the circuits from the remaining contacts 9| of the switches 01 include a-manually operated switch 93 for the purpose of at will cutting out any harmonics of like degree of the fundamental sound. In series with these switches 93 is one of a plurality of other variable resistances 94 each varying the intensity of harmonics of like degree controlled by one of a plurality of manually operated flexible rods 95, each rigidly supported at one end 96, each of said rods may have various curvatures of fiexure as previously mentioned whereby the relative intensity of the harmonics may be selectively varied. In series with these variable resistances 94 is one 'of a plurality of other variable resistors 92h for individual harmonic intensity control. In series with each of the last -mentioned resistors 82h is one of a plurality'of electromagnetically operated switches 95a which may be opened or closed by one of a plurality of relay circuits 86 which include a manually operated inductance 91 and a switch 98 also operated by the key I9 for introducing a variable harmonic time lag. v From each of the switches 95a the circuits are joined and again divided, one path being provided through a resistance 99 thence to a ground I00 through a grid-biasing battery IOI. In another circuit from the switches 95 is a coupling-com denser I02, a grid leak I03 to the grid-biasing battery IOI and thence to the ground I00. The grid leak side of the coupling condenser I02 is connected to a grid I04 of a four element thermoionic tube I05 the plate circuit of which contains a loudspeaker I08. Independent means for con trolling the sound from the loudspeaker I06 is provided by means for controlling the potential on a second grid I01 of the tube I05.

A means for. varying the potential on this second grid I 01 consistsof a plurality of resistances I08 each of which may be connected singly or in parallel with one or more of its companion resistances by means of one or more of a plurality of chord intensity control switches I09 also operated by keys of my keyboard, together with a variable resistance IIO having a plurality of taps for obtaining equal sound gradations or a second variable resistance III which may be optionally operated together with a movable contact of a potentiometer I I2 and'a battery II3 which furnishes current for operating said potentiometer.

The closing of all of the switches I09 would permit the maximum current to flow through the parallel fixed resistances I08 while the resistance 4 H0 provides a means for obtaining equal gradations of sound and the resistance III provides an alternate means for obtaining unequal gradations of sound.

In Figure 10 there is shown a portion of an alternate form of the records 8 which may be used with either of the modifications illustrated in Figures 11 and 12. In this form graduation of light intensity is obtained by varying the outline of my light openings instead of by gradations in the translucency of the openings shown in Fig. 2.

In this modification an opening II4 of sinusoidal outline corresponds to the lowest note and following notes as far as an inner opening I IS in radial succession comprise the remaining notes of the lowest octave. A pair of openings I I3 and I I1 each of sinusoidal outline corresponds to a note an octave higher than that corresponding to H4 which also represents the first harmonics of the v outer opening H4 in the first radial set of openings but their total width at their bases is just equal to that of H4, which is also equal to the distance between adjacent slots in a. corresponding annular ring of slots in my revoluble disk I. The notes of higher pitch than the pair H6 and 1 follow in radial succession toward the center as in the first radial set of openings. In succession other radial lines of openings, each corresponding to harmonics of the fundamentals in' the first radial line are provided and these will be formed with openings having 3, 4, 5, 6, '7, 8 up to n crests, which would correspond to-the fundamentals of the harmonics in the first radial line. 'In this modification of my record the radial lines correspond to a single octave instead of two I as in Figure 2, because each of the modifications with which it is used is provided with an inde-. pendent note control, making possible the playing of any chords without the complication involved in the use of my first form of record.

The stationary screen 6 and 6' of Fig. 1 and variously designated in the other modifications containing a number of light transmitting openings, each comprised of one or more shaded portions in sine wave proportions, may be made from a photographic plate by moving it in front of a a narrow beam of light either with uniform motion and a varying beam of light either with uniform motion and a varying beam intensity or with a constant beam intensity and a varying rate of motion. By the latter method the time rate of exposure during the making of one of the sine wave shadings of any one composite light opening is effected by the rate of translation produced a by the thrust of a cam during one half of a revoreduce spherical aberration, and is focused by a lens I24 through a second shield I25 provided with an opening I26 serving to confine the light beam:

to a restricted area on a photographic film I21 on a revoluble disk I28 mounted upon a shaft I29.,

The shaft I29 may be moved intermittently through angular distances corresponding to the shading of a single sine wave to be recorded such as my light transmitting openings 22 or 23 (Fig. 2). When my openings correspond to a plurality of sine waves each wave would be recorded in succession.

On Figure 14 there is also shown a mechanism which I have provided for moving my disk I28 and the sensitized film carried thereon which consists of a pinion I30 mounted on the shaft I29 and movedby a rack- I3I (which may have a length equal to the circumference of the pinion I30), which is intermittently coupled by an electromagnetic clutch I32 to a bar I33 pivotally attached to a vertical lever I34 provided with a slot I35 jor permitting limited longitudinal movement of the pivoted connection with said bar I33. The lever I34 is pivotally mounted upon a support I33 and at the opposite end is provided with a plurality of transverse holes I31 for varying its effective length. A spring I38 engages the upper end 0t said lever which is coupled by means of a link I33 to a reciprocating cam follower I40 which is driven by a cam I mounted on a shaft on which a contact commutator I42 also revolubly mounted. The commutator I4 is connected by means of wires I43 and I44 with the electromagnetic clutch I32 and in a second circuit I45 and I45 with the lamp IIB (Figs. 13 and'14). Whenever the operative length of my lever is 15 shortened the photographic film is moved through a correspondingly smaller angle. The slow movement of this apparatus and the fact that the light source H3 is cut ofl by the commutator at the same time that the magnet releases the rack I3I will permit manual operation in switching oil a constant speed motor, (not shown) by which the cam" HI and commutator I42 are driven, to stop my mechanism when a record is .completed. I provide a suitable speed control 2 means (not shown) for at will increasing the speed of rotation of my cam I4I when the effective length of my lever I34 is increased, and vice versa.

As an alternative I may vary the intensity of thevertical line light source from the slit in the shield I2I. Either method will assure the recording of wave forms of uniform degree of varied shading regardless of their width. If the density of a developed photographic emulsion 35 were directly proportional to the light intensity or what amounts to the same thing, the time of -exposure, then the photographic plate might be moved in simple harmonic motion to produce the sine wave shading. This might be accomplished 40 in a number of ways but should a cam be used in a manner as illustrated then its outline may be obtained as follows.

Proportional parts of the ordinates of a sine curve taken at equal distances along the X axis may be marked off one after the other along a line passing through the fixed center of the proposed cam outline starting at any convenient distance from the fixed center of the cam outline. After dividing 180 of the proposed cam into a 5!) representative number of equal angular divi- 'sions the pi line of the cam will be formed by drawing a s 00th curve through the intersections of arcs drawn about the fixed center of the cam from the distances marked off on the above mentioned line passing through the fixed center of the proposed cam outline and corresponding angular radii in order.

Actually the density of the developed 'photographic plate is notxdirectly proportional to the G0 amount of light. It will therefore be necessary by trial to determine the relative density with varying amounts of light and use the data obtained to correct the length of the ordinates of the-sine curve accordingly before obtaining the 8 outline of the cam as above described for a given emulsion-to be used. Another method may be used for obtaining shaded composite waves in which the photographic plate is moved at a uni form velocity while the intensity of the light providing a transparent form, to 'be ,described later, in an opaque screen and revolving a slotted disk, similar to those used inthe instrument itself as in Fig. 1, I and I, in front of it. Parallel 75 rays of light of constant intensity passing beam is varied. This may be accomplished by through the slits and wave opening are converged upon a photo electric cell. The/amplified current from this cell isused to operate a glow lamp which will vary with the light incident upon the cell. A narrow beam of light from the glow lamp is allowed to fall upon a photographic plate moved at uniform velocity which when developed will form the required shaded waves. Since the density of a developed photographic emulsion exposed to light is not arithmetically' proportional to the amount of light falling upon it, the

form of the opening placed in front of the revoluble slotted disk may not be a sine wave. The proper shape to record a sine wave shading on the finished photographic plate may be obtained by first calibrating the system. This may be done by using an opening in the screen in the shape of a triangle. The resulting shaded photographic plate when its varying density is determined may be used to obtain values for altering the shape of a sine wave form so that the actual resulting variations in density will be proportional to a sine curve. To change the number of waves recorded in a given distance the speed ratio between the revoluble slotted disk and that of the moving photographic plate should be changed by suitable change speed mechanism. Variations in speed must be accompanied by proportional regulation of the light intensity reaching the photo electric cell.

A further modification ofthe musical instrun ent is illustrated in Figures 15 and i6 which utilizes electrical impulses generated from a modified cathode ray tube I41, in which I have substituted for the ordinary accelerating anode having a central hole, an accelerating anode I43 provided with anarrow slot I43 running substantially the full length of a cathode I here absorbing screen I52 and of suflicient area to intercept substantially all of the electrons passing through the openings I53. The usual bat- 'teries and filament rheostat are indicated, but

present no novel features.

In this modification my absorbing screen I52 corresponds to my stationary records Ii and 6' of the modifications shown in Figures 1 and 12 while instead of my light intercepting rotating disks I and I my deflecting plates I5I serve to successively sweep 'a cathode .ray across the openings I53 and upon my plates I54.

In Figure 16 there is shown a section of my cathode ray tube, taken at pinety degrees from that of Fig. 15, it may be seen that alternate plates I54 are in alignment with successive openings I53 of my absorbing screen I52. The remaining plates I54 shown as located behind solid portions of my absorbing screen I52 receive rays through another line of openings I53. Each of my plates I54 is connected with one of a plurality of double throw switches I55 and through .it may be connected either with a ground I53 or with one of a pluralityot harmonic regulat- 60 ductance which will 75 In in a row will also vary the pitch. My cathode pose of impressing a positive potential upon the receptor plates I54 above that of the screen I52 which is grounded. From the grid leak I03 the electrical impulses may be amplified by any suitable means, in this case a resistance-capacity coupled amplifier circuit to a loud-speaker I58 in which regulation of the volume of sound may be obtained by means of a potentiometer I58.

The electrostatic field between my deflecting plates III is varied to produce oscillations of the cathode ray which fall upon my receptor plates which is connected by wires I88 and I8I to a coupling coil I82 which is in turn inductively coupled to a coil I83, the effective inductance of which may be varied by selectively closing any one of a plurality of switches I84. The coil I88 is connected in series with an inductance coil I85, the efiective inductance of which may be varied by closing one of a plurality of switches I88. Connected in parallel with the coils I88 and I85 are a variable condenser I81 and a plurality'oi fixed condensers I88, each of the latter being selectively connected by one of a plurality of switches I89. These condensers and coils constitute an oscillating circuit and serve to determine the frequency of the fluctuations oi the cathode ray of the tube I41. e

For supplying power and causing oscillations to be produced there is connected between the coil I88 and the switches I88 an oscillating tube circuit consisting of two direct current blocking condensers I18 and "I, a three element electronic oscillating tube I12, together with a plate battery I18, a choke coil I14,

a grid biasing battery I18 and a filament heating battery I11. The portion or the coil I85 which is connected in the circuit as well as that portion of the coil I83 between the end switches I84 also serve as a coil in the feed back circuit to the grid, however a feed back coil of constant inductance may be inductively-coupled instead. Connected in parallel with the circuit of the coil it! are a plurality of coupling condensers I18 and I88 each of which may be selectively connected by one are. plurality of switches. I8I or I82 respectively. 7

Each of the switches I88 is controlled by a key of my keyboard, which represents an octave also controlling a switch IBI while each of the switches I 88 is connected to one of a difierent set of keys which also operates a corresponding one of the switches I85. The connections to .the coils I88 and I85 are each made to give amounts of inproduce the pitches of the just tempered scale.

A variable condenser I8! is connected in parallel with the condensers I18 for compensating for any variations made by means or the variable condenser I81. Similarly each of a plurality oiv be connected in pa- 1 .fixed condensers I84 may rallel by one of a plurality of switches I85 by a key which simultaneously closes a corresponding switch I88 to a fixed condenser I88 in the oscil- Toiatingcircuit.

In this modification variations of rapidity of oscillation of the cathode ray across any row of openings I5I or-my screen I52 varies the pitch, while the variations in the number of openings a grid leak I15,

tube I41 with the special form of screen I52 need not be changed'tc produce desired sounds, and

it is desirable to maintain the amplitude 01 oscillation of the cathode ray substantially uniform during the operation or my instrument. This may be done by introducing one or more of the coupling condensers I18, I88 and I84, to compensate for any changes 01' frequency in the oscillating circuit.

The rapidity of these oscillations may be varied by changing the amount of inductance or the capacity of the oscillating circuit and this may be done by means of my keyboard keys and other manually operated parts. The keys I88 are used to change the pitch within one octave, the keys I88 The deflecting plates I 5| constitute a condenser the key signature key, and need be changed only one key signature to anwhen changing from other, the remaining switches being open.

In order to obtain the equivalent of sine wave proportions with this modification of my invention, I have modified the shapes of the openings I53 as indicated in Fig. 17. This curve was obtained by first plotting a sine wave curve of a height desired for my record; then dividing the distance between adjacent minimum ordinates into equal parts, and measuring the ordinates at these points; secondly plotting a second sine wave curve of a height equal to a desired width of record and dividing the distance between its adjacent maximum and minimum ordinates into a number of equal plying the arbitrar' y chosen number 01' parts used for said first wave by'the number of openings desired in the selected line; next drawing ordinates from these points to the curvepthen from the intersections thus determined, drawpoints which, when joined, determine the shape of opening or openings desired.

Figure 18 illustrates a further modification of parts determined by multi v the form of my invention shown in Figs. 15 and 16 in which I have substituted a modified "relaxation circuit" for the sweep circuit identified in Fig. 15 by the numerals I88 to I85 inelusive. The wires I88 and IN from the defiection plates iii are shown for the purpose of indicating the points or connection of this modified relaxation circuit. An ordinary three element thermionic tube I88 having a filament I81 agrid I 88 and. a plate I89 and a filament heating battery I98 is connected with the filament I81 and plate I88 in circuit with a condenser nected with a plurality of key board operated switches I88 arranged in parallel, a terminal one 01' these, switches being connected in series with a terminal one of a plurality of key signature controlling switches I98, the terminal one of the switches I88 being connected with the filament I81. These-switches I88 and I88 are connected and a battery 192., Connected in parallel is a vapor filled three and filament I85 of this tube are also connected to the deflection plates I5I or my cathode ray tube I41. The grid I8! is con- 

